Process for converting cellulose



III A.' KocIIIiR'. PROCESS-FOR CDIIIVERTING GELLUIOSE.

APPLICATION FILED IIIAILZII 9I. 1,3745928, Eamed Apr. l, 1921.

IIIIIII I magg? RUDOLPH A. ROCHER, OF SAN FRANCISCO, CALIFORNA.

.PRCESS FOR CONVERTING CELLULOSE.

refranes.,

Specification or Letters Patent.

ifatentedilpr. 19, 1921.

Application filed March 21, 193K?. Serial No. 156,303.

To all fro/wm t may 'co/acera:

Be it known that I, RUooLri-r A. Koorrnn, citizen oi the United States,and resident ot San Francisco, .in the county ot San Francisco and Stateor" California, have invented certain new and useful improvements inProcesses for (.fonverting- Cellulose, of which the following is a.specification.

My invention relates to improvements in processes for convertinglcellulose and is par ticularly adapted to the conversion of celluloseinto sugar or sugars such as glucose or similar ermentable productswhich may `be treated by fermentation 'methods for the production or'alcohol. a continuation in part of my prior application Ser. No. S5670liled Dec. 8, '1915, and a continuation in part of iny priorapplications Ser. No. 130563 liled Nov. l0, 191.6, and Ser. No. 132584tiled Nov. 2l, 1916.

lt has been known that cellulose can be converted to glucose bysuitable, treatment with acids such as sulfuric acid, sulfurous acid andhydrochloric acid. But in every instance, so far as l am. aware, theselection of reagents and conditions have been such that either thecellulose has only been partly converted or else the acid reagent hasbeen largely lost or so di'licult to recover or separate that theprocesses have failed in conimercial operation.

When suitable cellulose material is conu verted according to my process,not only is thev desired large yield obtained, but .the treating reagentis used in so small an amount that the most orf it is easily recovered,so that it may be used over and over again and also the reaction is moreefficiently obtained. Further objects, features and advantages will moreclearly appear from the detailed description given below, taken inconnection with the accompanying` drawing;

which forms a part of this specification andv which illustrates aconverter, largely iu secu tion, adapted to carry out the process in oneform.

According to onemode of carrying out Athe process, cellulose material,such as saw dust or wood chips containing 30% to 10% by weight ofmoisture (wa-ter) are fed in to the airtight converter 'l th rough topInanhole opening. Such saw dust or wood chips may contain about 70% otcellulose, based on the dry *weight of the Wood.

The converter l is provided with a stirrer or agitator comprisingr twospiral blades 2 rlihis application is A and 3 which run close to thecylindrical. wall of the converter'. The scraper blade 2 has such acurvature that it tends to force the material longitudinally of theconverter in one direction while the scraper blade 3 is curved in theopposite direction so as to tend to force the material in the oppositevdirection llongitudinally of the converter. Preferably there is anotherpair of blades similar to the blades' 2 and 3 but arranged on theopposite side ol the converter'. The agitotingV blades are carried by ahollow central shaft 4: passing' through a stuffing' box at 5 andhaving` a .bearing Aat 6 inside the converter. A gear 7 is secured onthe end of the shaft l which gear meshes with a gear 8 on a shaft 9which is driven from any suitable source of power. The converter isbrovided with a jacket l0, through which water or other cooling,` fluidmay be circulated by means of pipes ll and l2 by opening the valves 13anilla; or the converter may be heated by circulating steam or otherheating fluid through the jacket by means of pipes l5 and 1G byoperating the valves 17 and 18. It desired, a heating Huid or a coolingfluid may be introduced into the hollow shaft et. A thermometer 19, apressure gage 20 and a vacuum gage 2l. are connected tol the converterto indicate the conditions of temperature, pressure and exhaustiontherein.

After the sawdust or other cellulose ma tcrial, containing about 30% orLl0% of moisture has been charged into the converter, the air isexhausted from the converter by any suitable evacuating,apparatusconnected with the pipe After the removal-of the air, hydrochloric'acidgas is admitted to the converter through the pipe 23 during` agitationof: the cellulose material. Although the pressure in the converter maybe little'or nothingy above atmosphere pressure, the sawdust and thewater therein will, under these conditions, absorb so much of thehydrochloric acid that liquid hydrochloric acid will. be formed of astrength of 39% or over. It is important that acid or this strength beproduced, as otherwise full conversion or' the cellulose will not beobtained. It the temperature or conditions be such that acid of thisstrength is not formed, the ditiiculty may be remedied by slightlyincreasing the pressure within'the converter as by introducing the HC1gas underpressure The absorption of HC1. gas

. drochloric acid in the by the Water or moisture raises the temper'ture of the mass and in order that such increase in temperature may notreduce the strength of the liquid hydrochloric acid by driving off theHC1 gas therefrom, it is genn erally necessary to cool the mass, unlessthe pressure is high, which cooling may be done by circulating a cooling:fluid in the jacket l as above described. In treatments which l havecarried out, l 'rind that after from 2e to 72 hours practically 100% oithe cellulose will be converted.. .lt is not necessary that the mass becontinually agitated after it has once been thoroughly mixed and theWater therein has absorbed sufficient HC1 gas to produce `liquidhydrochloric acid of 39% strength or over.

l understand that the action in converting" the cellulose to glucose isa hydrolytic action, the cellulose taking up molecules of Water and theHC1 acting as a catalytic agent. Other halogen acids, such as liydrogeniodid, may be used, but it is important that the halogen acid be of thecritical strength, Whic as above explained, is 9% or over in the case ofHCl, in order that the required yield may he obtained. Authorities givethe critical strength oi' hydroluoric acid as from 70% to 75% and thecritical strength of l'iydrobrornic acid as about 66% or over, While thecrieical strength of hy'driodic acid is believed to be about 68% or overwhen used hot as above 160 C.

After the conversion is completed, the HG1 gas in the converter may bewithdrawn therefrom and stored, 'for further use by suitable evacuatingapparatus. There will then remain a small amount 'of liquid hymass. Byincreasing the temperature and evaeuating the converter, this may belargely removed, the liquid acid first giving; oil HC1 gas 'until the)strength of the acid has been reduced to about 26% and then hydrochloricacid of about this strength being distilled oil. This may loo saved andused to furnish part of the liquid ecid for another hatch. A. suitableapparatus for accomplishing these obis shown in my copending applicationSer. No. 151175, 'iled Feb. E27, 1917:

By inciting the amount of water used in the treatment to an amount lessthan the Weight of the sawdust and preferal'ily to from to l the Weightof the Wood material, not only is there much less liquid hydrochloricacid to be removed. after the `convertsion, but the Water present isbelowY .the amount 'which would render fluid any sub` stantial part ofthe mass by forming i. solution oi'" the glucose or other soluh'e conversion product. li" much of the mass is rendered fluid, `causes thematerial to ball up and so prevents all parts of the cellulose materialciiiciently acted upon rrom being,y and hence results in a` loss or elsean undue amount ofi time in bringing about the con version.

After the small amount of acid present has been. largely' removed asabove de scribed, suilicient Water may beadficd to make a glucosesolution of the desired con sistency and then the material lremoved fromthe converter through the bottoni manhole and treated by a suitabletermen tation process to produce alcolici.. necessary to remove theunconrertcd iignin of the Wood and the small amount ci acid remaining:`in the does not necessarily interiore materially with the fermentationprocess.

l find 'that the converting` action can be greatly hastened, if thetemperature be increased slightly above room temperature. ln order thatsuch increase in temperature may not cause the strength of the. acid tofall below the critical. strength (39% if HCl, be used), l increase thepressure with in the converter. This may be done by charging theconverter witi' the halogen acid gas under pressure. 'A have obtainedexcellent results by keeping the temperature at between flOO and 6G@ C.and the pressure of the HCl between i() and 60 pounds per square inch.The ,greater the pressure, the quicker the desired. or critical strengthof acid. is formed with the Water or dilute acid already in thematerial, l prefer to use approximately saturated acid, which should beif HCl is used. and the strength of saturated acid is of coursedifferent for di `.ti'erent temperatures and pressures. so 'that forincreases of tempera ture, as `for erainpleirorn 40 C. to 60 C., thepressure must be raised to maintain, the acid to the critical strength.'to 100 lbs. pressure is generally sulicient. By using such increases lutemperature and pressure.y have brought about substantially con pleteconversion of the cellulose in from to 9; hours.' The higher thetemperature used. and the greater the strength of ecid used, the shorterthe time it takes to produce the desired conversion. if desired. the,saturated acid of critical vstrength may be- `termed at substantiallyroom temperature and then later the conversion hastened by increasingrthe temperature. Where the acid is brought up to critical strength byabsorption of gas the heat produced by the absorption ofthe Hill ,grasmay be used to accelerate the hydr'ilvsis., ln en actual trial, l" Foundtime si lust, which stoodin.

l,Contact with hyfrcchhiric acid off 42% strength, had reached themaximum conversion. after stando-:1g for l, hourat 40 to-{lo C., and inone lxallf hour at aboutGOo C.

lftlie treatment is such that the cellules' is not only converted toglucose, but the glucose to some extent been reconvertecl to othermaterials, then the mass may be It unii il t suitable apparatus.

batch maybe further-dilutedy when vit is. Vready for fermentation',

boiled with water,or the solution heated to 1100.0., to recouvert thesematerials to glucose or similar' .fermentable products.` The amount ofwater used. is preferably such as converterfthe heat being 'applied byturnor thisstep `may be carried out in anyother vFollowing this step thealthoiigh, if desired, the insoluble residue consisting 'mostly' ofllignin"may be first separated from the` dissolvedglucose. I

i therefrom; and then dilute hydrochloric acid water ,present If inthebeginning, the sawdust does vnot .contain suiicientmoisture or water,a suf i'cient. amount'. offwater or hydrochloric acid may be added. "Ifdesired,-the` wood may first be` dried to remove the moisture addediintilfthe desired amount of waterfis .present in .the mixture.,v Theamount of should be at least 10% of the weight of the cellulose, assubstantially this amount i-s'necessaryfor the hydrolysis ac- .vcordingto'the formula Besides wood, numerous other cellulose substances may betreated according to the invention, as for example, hydro, hydratoandoxycellulose, as well as cellulosewhich exists in combined form;

Instead (informing the acid O f'" naar strength a situ in the yInateria`l by admitting the liquid acid of the 39% to 40% strength if' HG1 isused) may be mixed withthc cellulose containing-"material. 1n such case,however, the. material usually contain. trom shoulddirst' be dried orVtreated so. as toremove substantially all the water or moisture'therefrom, as otherwise, such water or moisture would reduce thestrength. of the acid below the critical strength assoon as it becamemixed with the material. Wood waste, l sawdust, plant stalks, straw andthe like 5%1 to 35% of moisture. However, if the moisture in the cellulose material be so smalland the strength d chloric acid, and thenadding water to the the critical value, such drying or removing vof,moisture may be omitted.

Many other changes and modifications I may `also be made withoutdeparting from i by Letters Patent, is:

the spirit and scope of the invention in its broaderv aspects.

What I claim as newand desire to secure 1. The process of l materialinto sugar or sugars, which consists ing steam into theja-cket or'byturning steam. -directlyvinto thei material injthe converter,

" material being treated. f c converting vcellulose the so-treated massto the actionlof, h

'at a temperature of at least 15 y represents at least 10% or"the-cellulose converting cellulosic in treating the cellulosi-c materialAwith hydrochloric acid of at least 39% strength, the i amount ofwatenpresent beinglbelothe ramount required torender the resulting'mass"39% strength, the total amount ofwa'ter being less in weight than theweight y.of the 3. The rocess of which consists in hydrolyzing the samewith hydrochloric acid of at least 39% strength in an atmosphere of HC1gas, the amountof water present beingv below thexamounuwlilch i wouldyrender iuid any substantial partoi the mass.

The process of converting which consists in treating the celluloseoirtaining substance to lmake the moistuieoon- La tent thereot` aboutoneliali1 part byweight of thecellulose to be converted, subjectingchloric acid gas in a closed contains all the materials present aresaturate and maintaining an excess of gas 1n the container while themass in said container is kept at atemperature of at i 'i yleast as highas room temperature and at a at least as great as atmospheric pressureJfor a period of time sulicient to convert thelcellulose 'contained inthe mass into lucose, or-sugars. l

5. heprocesstor converting cellulose,

' which consists in treating a 'comminutedcellulose-containing substancein such away as 'the Igas to' form lhydrochloric acid of at least il?!"39% strength,

to effect an equal'distrib'ution of moisture through 1the mass so thatthe water content thereof is is in a closed'container to ,hydrochloricacid gas until the moisture and .other constituents of the mass aresaturated with the hydrochloric acid gas vto forin an acid of at lessthan the weight of the mass, subjecting lthe moist massf while -the sameleast 89% strength, maintaining an excess of hydrochloric acid gaswithin the 'container while the'masswithin is ma i ntained atl apressure at least as great as atmos heric and until the hydrolysis ofthe cellulose in the'mass'V is` complete, eliminating the excess ofhydroi'nass within-the container to dissolve the glucose present in thetreated mass. J

6. The herein described process for converting cellulose, which consistsin ,tre'ating a f i cellulose-containing substancejinsuch a' manner thatthe water present in the mass be converted, and not in such excess aswould j of the cellulose to be converted, allowing,` hydrogen chloridgas to Contact with the moist mass so as to saturate the moisture andother substances contained 1n the mass to form hydrochloric acid of atleast 39% strength at a pressure at least as high as atmospheric and atroom temperature, and maintaining an excess of hydrogen chlorid gas incontact with the mass while the Whole is kept in a closed container at atempera.- tureof at least l5o C. until the hydrolysis of the celluloseis completed.

The process fof treating cellulose, which consists in hydrolyzing thesame with hydrochloric acid of 89% strength or more, in an air-tightcontainer containing an atmosphere of HC1 gas Without air, t0 preventthe strength of the hy'drolyzing acid falling below the criticalstrength of 39%, the amount of water present being less than the Weightof the material being,r treated and nsulcient in cmount to render Huidany substantial part of the mass whereby the tendenc of the mass to ballup upon being agitate' -issubstantially eliminated, and the HC1 may beeiciently used and yet practical quantitative hydrolysis of thecellulose obtained. y

8. The process'of treating cellulose which consists in. hydrolyzing thecellulose with a halogen acid of 39% strength or over and of criticalstrength in the presence of halogen 4acid gas under pressure greaterthan atmosphere, the amount of water present heilig less by Weight thanthe dry Weight of the material being treated.

.9. The process of converting cellulose which consists in treating;cellulose material with hydrochloric acid of 39% strength or more, theamount of Water present being insuiicient to render luid any substantialpart of the material, and then distilling' off the hydrochloric acidbefore any substantial amount of Water has been added to the convertedglucose.

Si ned at Decatur in the county of Adams and tate of Indiana this 16thday of March A. D. 1917.

RUDoLPH A. KocnER.

